EP0051780A1 - Dispositif pour économiser la puissance électrique pendant le démarrage et la commande de moteurs asynchrones à courant triphasé - Google Patents

Dispositif pour économiser la puissance électrique pendant le démarrage et la commande de moteurs asynchrones à courant triphasé Download PDF

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Publication number
EP0051780A1
EP0051780A1 EP81108861A EP81108861A EP0051780A1 EP 0051780 A1 EP0051780 A1 EP 0051780A1 EP 81108861 A EP81108861 A EP 81108861A EP 81108861 A EP81108861 A EP 81108861A EP 0051780 A1 EP0051780 A1 EP 0051780A1
Authority
EP
European Patent Office
Prior art keywords
voltage
phase
motor
control
set forth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP81108861A
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German (de)
English (en)
Inventor
John Gordon Rutherford
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
STEADFOLD Ltd
Original Assignee
STEADFOLD Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by STEADFOLD Ltd filed Critical STEADFOLD Ltd
Publication of EP0051780A1 publication Critical patent/EP0051780A1/fr
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1892—Arrangements for adjusting, eliminating or compensating reactive power in networks the arrangements being an integral part of the load, e.g. a motor, or of its control circuit
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/26—Power factor control [PFC]

Definitions

  • the invention comprises an electric alternating current induction motor controller for saving electric power in respect to the electricity used for starting and running such motors and particularly three phase motors.
  • This electronic device develops and improves the Power Factor Controller that is the subject of United States Patent Number: 405.2648 invented by Francis J. Nola and entitled "Power Factor Control System for A.C. Induction Motors".
  • the present invention comprises a power saver which controls the voltage applied to a three phase, three wire star or delta connected induction motor.
  • the power saver operation is based on a correlation between motor torque and power factor.
  • the power saver monitors the power factor and adjusts the voltage applied to the motor to compensate for changes in load.
  • the present invention uses full wave current and voltage sensing on all three phases. Voltage control in the present invention is achieved by the use of phase controlled thyristor switches. Full wave voltage control has been used in preference to half wave voltage control because of the greater electricity savings that can be made and because of the generation of even order harmonics and D.C. polarisation by the use of half wave voltage control.
  • Full wave power factor sensing is conducted on all three phases with a composite control voltage derived from the summation of all three phases giving effectively six samples per cycle thereby enabling a faster and greater response and greater system stability.
  • Voltage references are achieved by monitoring voltage Between phase and star point of three wire star configured control circuitry. Such star point is generated by the circuit configuration, this method of voltage referencing Ls achieved independently of phase rotation and, unlike phase to phase references, prevents any confusion when connecting up the unit in use with a motor. Motor current reference is derived by monitoring voltage across thyristors.
  • the reduction in start current associated with the use of soft start enables the use of lower rated switching thyristors for a particular installation hence reducing the overall cost of the unit and accordingly the payback period related to the electricity savings achieved in the commercial operation of a motor controlled by the power saver.
  • a comparator '5' monitors the polarity of the voltage between the star point and phase to generate a voltage reference 'a'.
  • a second comparator '6' monitors the polarity of the voltage across the thyristor switching element 'O-M' to generate the current waveform 'b'.
  • the outputs from the comparators are connected to an opto coupler '7' in a logic OR configuration such that current flows through the opto coupler when voltage and current polarities oppose 'c'.
  • a capacitor '8' is connected across the voltage comparator '5' to introduce a twenty degree phase delay to enhance composite signal processing.
  • the resultant power factor waveform 'c' has a mark space ratio proportional to the power factor.
  • the three full wave derived power factor signals 'd' 'e' 'f' in fig. 4 from the three opto couplers are summed 'g' and passed through a single pole resistor capacitor low pass filter '9' and '15', to a response shaping active filter generating the composite control voltage 'i' for controlling the firing delay angle.
  • Power factor operating point is adjusted by the offset current from a trimpot '14' to the input of the low pass filter operational amplifier '10'.
  • Thyristor firing enable signals for each phase Fig. 5 'n' are derived from a voltage comparator '17' comparing the composite control voltage 'i' and a voltage ramp 'm' which is reset by a zero crossing detector '16' monitoring the phase to star point voltage 'j'.
  • the firing signals 'o' comprise high frequency pulse streams, transformer coupled to the thyristor gates.
  • the power saver incorporates two alternative starting modes for starting the motor.
  • Fig. 7 illustrates the overall configuration of the power saver showing the control sections for one phase only.
  • the low pass filter, high frequency oscillator and starter sections are common to all three phases, with separate zero crossing detector, ramp detector, comparator, gate and power factor monitor required for each phase.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Motor And Converter Starters (AREA)
  • Control Of Ac Motors In General (AREA)
EP81108861A 1980-11-04 1981-10-24 Dispositif pour économiser la puissance électrique pendant le démarrage et la commande de moteurs asynchrones à courant triphasé Ceased EP0051780A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU633680 1980-11-04
AU6336/80 1980-11-04

Publications (1)

Publication Number Publication Date
EP0051780A1 true EP0051780A1 (fr) 1982-05-19

Family

ID=3696875

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81108861A Ceased EP0051780A1 (fr) 1980-11-04 1981-10-24 Dispositif pour économiser la puissance électrique pendant le démarrage et la commande de moteurs asynchrones à courant triphasé

Country Status (1)

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EP (1) EP0051780A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2568735A1 (fr) * 1984-08-02 1986-02-07 Allegri Electricite Sa Dispositif d'alimentation d'un moteur electrique monophase ou polyphase
EP1215503A2 (fr) * 2000-12-18 2002-06-19 WILO GmbH Mesure du facteur de puissance
AT500258A1 (de) * 2002-07-31 2005-11-15 Va Tech Elin Ebg Elektronik Gm Verfahren und vorrichtung zum anfahren elektrischer maschinen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2006484A (en) * 1977-10-06 1979-05-02 Parker L W Energy economizer for induction motors
US4176307A (en) * 1978-05-17 1979-11-27 Parker Louis W Energy economizing AC power control system
WO1980002895A1 (fr) * 1979-05-25 1980-12-24 Scott & Fetzer Co Controleur du facteur puissance pour un moteur a induction

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2006484A (en) * 1977-10-06 1979-05-02 Parker L W Energy economizer for induction motors
US4176307A (en) * 1978-05-17 1979-11-27 Parker Louis W Energy economizing AC power control system
WO1980002895A1 (fr) * 1979-05-25 1980-12-24 Scott & Fetzer Co Controleur du facteur puissance pour un moteur a induction

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Electrotechnische Zeitschrift, Publication A, Vol. 100, No. 24, November 1979, Berlin (DE) J. Gambel: "Wie Man Motor-Blind-Leistung Reduziert", pages 1397-1398 * page 1397, middle column, line 1 to right-hand column, line 54; figure 2 * *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2568735A1 (fr) * 1984-08-02 1986-02-07 Allegri Electricite Sa Dispositif d'alimentation d'un moteur electrique monophase ou polyphase
EP1215503A2 (fr) * 2000-12-18 2002-06-19 WILO GmbH Mesure du facteur de puissance
EP1215503A3 (fr) * 2000-12-18 2003-12-03 WILO GmbH Mesure du facteur de puissance
AT500258A1 (de) * 2002-07-31 2005-11-15 Va Tech Elin Ebg Elektronik Gm Verfahren und vorrichtung zum anfahren elektrischer maschinen

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19830118

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Effective date: 19851011

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Inventor name: RUTHERFORD, JOHN GORDON